Light beams or optical signals are frequently used to transmit digital data between electronic devices, both over long distances and between adjacent circuit boards or even between components on a single circuit board. An optical signal may also be used for other purposes including position or motion sensing, measurement, reading encoded data, etc.
Consequently, optical technology plays a significant role in modern electronics, and many electronic devices employ optical components. Examples of such optical components include, but are not limited to, optical or light sources such as light emitting diodes and lasers, waveguides, fiber optics, lenses and other optics, photo-detectors and other optical sensors, optically-sensitive semiconductors, and others.
An optical communication system typically involves taking an electronic signal and converting it to an optical signal for transmission through an optical medium. Once the optical signal reaches its destination, it is converted back to an electrical signal so it can be processed by digital logic circuits.
The receiving end of the optical communication system typically involves a receiver circuit which includes a photodetector. The detector, which may be a photodiode, converts an optical signal into an electrical current. The receiver circuit then takes the electrical current which has been generated by the photodetector and amplifies it to a voltage level suitable for standard digital logic circuits.
The receiver circuit performs important amplification and filtering operations to produce a voltage signal that is compatible with the digital logic circuits. Receiver circuits typically consist of a trans-impedance amplifier or a sense amplifier. While these amplifiers may perform the desired amplifying function, they consume a relatively large amount of power and can often generate undesirable noise, jitter, and delay. Ideally, a receiver circuit would consume much less power and produce significantly less noise, jitter, and delay than implementations which use trans-impedance and sense amplifiers.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.